The basic building blocks of a cellular communications device such as a cellular telephone (cell phone) are generally well-known. They include an antenna, a liquid crystal display (LCD), a keypad, a microphone, a speaker, and a battery. A circuit board provides interconnection between these various components. The circuit board requires most of the engineering involved in designing and building the device. It runs device software applications and processes Input/Output (I/O) to device hardware.
Most of the engineering required in designing and building a circuit board is directed to the radio stack and call processing. Advanced engineering is needed to successfully implement the desired functions. Radio stack and call processing components must also comply with a host of externally-imposed requirements, for example regulations imposed by the Federal Communications Commission (FCC), and accepted industry standard communications protocols. Furthermore, because the radio stack and call processing are fundamental to the basic operation of a cellular communications device, it is essential that the design be both high quality and cost effective to meet demanding consumer expectations.
Pre-engineered, pluggable communications modules currently exist for laptop computers. In general, these modules are designed to communicate using the popular 802.11 Wireless Local Area Network (WLAN) communications protocols. They interface with laptop electronics using the mini Peripheral Component Interconnect (mini-PCI) or PCI Express (minicard) interfaces. Recently, new laptop centric modules employing Wireless Wide Area Network (WWAN) cellular communication protocols are becoming available. Examples of such data communications modules are the NOVATEL® model EU730, SIERRA WIRELESS® MC8765.
However, such pluggable communications modules have not been widely adopted in cellular communications devices. For example, cell phone manufacturers continue to integrate radio stack and call processing functions into the more general purpose circuit board, despite the expense of doing so. This is due, at least in part, to the unavailability of an inexpensive, pluggable universal radio module that can benefit from economies of scale in manufacturing, can successfully interface with host electronics, and can fit most desired cellular device design specifications.